IN the old days, a big posh car would have four doors, a boot and almost certainly rear drive.

Simple. No SUVs, no hatchbacks and definitely no fancy ‘sportbrakes' or ‘sportswagons'. Which must make the Lexus GS something of a throwback, you'd think, because visually it adheres to the original formula.

But there's one particular difference that transports the rather stately looking saloon right into contemporary times - it's a petrol hybrid which means it's powered partly by an electric motor and partly by a conventional engine.

There are several main aims in this route of design. Firstly to reduce fuel consumption, also to cut emissions and additionally improve refinement by providing quieter running. All laudable objectives, especially in a luxury model.

Available in either 300h form or as a 450h, I went for the less powerful model which focuses more on luxury and refinement than pace. The first thing you notice when starting is the serene quietness with which the Lexus glides away from a standstill.

Even when the petrol engine strikes up after a few metres its involvement is almost imperceptible.

The flow of power from the 2,494cc, 4cyl engine plus the electric motor is smooth without being potent. 62mph comes up in a modest 9.0 seconds but the CVT automatic gearbox is slick and efficient in providing effortless progress.

It's at its best cruising and can prove a trifle slow witted if you try to hurry it along. The steering, also, is biased more towards comfort rather than sport and soaks up road irregularities well but offers little in the way of feedback.

Although official fuel figures and CO2 levels are towards the top of its class with combined consumption at more than 60mpg and emissions of 104g/km, in real world surroundings my average was around the 35mpg mark. The GS is is after all a large, heavy five-seat saloon.

Cornering is safe and predictable without being particuly responsive. As with the steering, the emphasis is primarily on comfort. Ride standard is excellent with good suppression of road irregularities. Roll and vertical suspension movement is well damped.

Lexus has earned a high reputation for providing a good cabin environment with quality fittings and sound build quality. The seats are comfy and supportive with 18 electrical adjustments. The steering wheel can also be adjusted electrically for height and reach.

A 12 speaker audio system with CD player is standard as is leather trim, heated seats, dual climate control and sat nav.

A huge 12.3-inch infotainment screen dominates the fascia and incorporates the sat-nav. It's a bit fiddly to use, especially on the move over a bumpy road surface.

Although the rear seats neither split nor fold, boot space at 450 litres is generous enough for most families despite the under floor batteries taking up some room.